Gas valve



March 31, 1964 F. c. GALLEY GAS VALVE Filed May 11, 1960 a A 6 @-14 wz u am n. nu 4 1( L V4 w. l 1, d a 1 M /L 8 Z MZ d. 4.1 3 1.: 0-., .M .fz 2 .4 L 4 L f E .VE ./fh l 4 M T/l//l//l///////////////////// z m M M .u. R onu c mML M A w. 4 8 C h.. m 3 E o N, w E 0 N00 E R a f w 9 .l. l Y B 7N uw@ t4 (Il o 6 5 United States Patent O 3,126,911 GAS VALVE Fred C. Galley, Detroit, Mich., assigner to American Radiator & Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed May 11, 1960, Ser. No. 28,452 12 Claims. (Cl. 137-495) This invention relates to a gas valve and particularly to a gas valve having improved pressure regulation features such `as to especially adapt it for use with conventional gas-red domestic heating systems.

In conventional domestic heating systems the burners are arranged within combustion chambers which feed the products of combustion upwardly to a stack or flue. During the shut-down periods a static col-umn of relatively cold air builds up in the flue. IDuring start-up of the furnace the lstatic column of air in the stack acts as an :obstruction to the immediate discharge of the products of combustion from the furnace. Before this static column of air can be moved out of the stack the fuel `gas piles up in the combustion chamber and tends to cause a Vsmall explosion therein. In this connect-ion the small pilot flame does not completely or thoroughly ignite the large quantity of fuel gas being fed through the main burner `so that the sta-tic column of air works on a relatively large volume of ra-w gas to bottle same up in the combustion chamber.

In some instances the resul-ting explosions or pops during the furnace start-up period are so substantial as to burst open the combustion chamber door and ignite dust and the like located outside the furnace. There is, therefore, a considerable safety hazard which it is desirable to overcome. Under the present invention it is proposed to overcome this disadvantageous condition by the provision of a gas valve having a novel arrangement of part-s whereby during start-up of the furnace the pilot ame is fed with a relatively small quantity of fuel gas so as to eliminate the above-discussed tendency for the build-up of explosive mixtures in the combustion chamber.

The valve of the present invention provides the abovediscussed small gas flow during furnace start-up, but special provisions are also made whereby the full capacity of the valve is `automatically delivered during the period of operation after initial start-up. Further, special provisions are preferably made whereby to achieve a controlled closing of the valve during the automatic shutdown period.

In this connection it is here noted that various burners and burner-chamber arrangements impose diiferent elo-sing requirements on the gas supply valves.

In most burners of the upshot type the primary air 4is introduced into and mixed with the fuel gas in a Venturi which leads to the burner nozzle or head structure. As the primary air-fuel gas mixture flows through the nozzle orifices the secondary air from around the burner head is introduced into the mixture so as to better promote the combustion process and `extract the desired B.t.u. values from the gas. The pilot flame is of course located closely adjacent the burner orifices to ignite the main gasair mixture during furnace start-up.

In some burner-combustion chamber arrangements a slow or unregulated cut-off of fuel gas to the burner results in a tendency of the main ilame to travel backwardly within the burner head so as to produce an audible pop or back're. In some cases this backward propagation of the flames `snuis out the pilot llame.

In order to overcome these disadvantages the present invention proposes an arrangement wherein the cut-off of fuel gas to the burner can be very accurately regulated or controlled, particularly as regards the rate of closing.

41From the above it will be seen that one object of the 3,126,911 Patented Mar. 31, 1964 ICC 2 present invention is to provide a gas valve which has improved control of the gas flow during all periods of operation including burner start-up, main period of operation and burner shutdown.

A further objective of the invention is to provide a gas valve having a control arrangement whereby the valve is enabled to deliver a relatively small charge of fuel to the burner during the start-up period, thereby to eliminate the tendency of the furnace to pile up raw fuel gas in the combustion chamber in -a manner to cause explosions and pops.

A further object of the invention is to provide a gas valve which may open to the full pressure at a relatively slow rate and if desired close to zero pressure at a relatively -fast rate.

A further object of the invention is to provide a gas valve design wherein the opening and closing characteristics of the valve may be controlled and varied in accordance with different burner designs without making substantial changes in the construction of the valve, thereby enabling the manufacturer to produce a line of Valves to suit variations in installation conditions.

A11 additional object of the invention is to provide a gas valve for domestic gas burners wherein the valve compensates for faulty design of the burner, eliminates a potential safety hazard, improves burner performance, reduces fuel consumption, and reduces losses encountered by reason of escape of unburned fuel gas to the stack.

Other Objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIG. l is a sectional View taken through a gas valve constituting one embodiment of the invention..

FIG. 2 is a sectional view taken on line 2--2 in FIG. l.

FIG. 3 is a sectional View taken on line 3-3 in FIG. l.

FIG. 4 is a sectional View taken on line `4---4 in FIG. l.

Before'explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since .the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings and particularly FIG. l there is shown a gas Valve dened by the three valve bodies 1t), 12 and 14. Valve body 10 is provided with an opening 16 therein which is suitably threaded or tapped to form a mount or connection for a gas supply inlet line (not shown). In operation the inlet gas is directed through the opening 16 and into an inlet chamber 18 formed by the partition 20, said partition having an opening therein defining a main port 22 for the flow of gas to an outlet chamber 24. The outlet chamber communicates with an opening 26 which is suitably tapped or threaded to form a connection or mount for a discharge line (not shown) leading to a gas burner for a domestic furnace.

The flow of gas through port 22 is controlled by a flowthrottling valve element 28 which is connected to an operating diaphragm or movable wall 30 by means of the stem 32. The central portion of the diaphragm preferably carries a metal disk 34 which prevents the diaphragm central portion from flexing o r wrinkling, the arrangement being such as to enable the diaphragm to move up and down substantially in the manner of a piston for closely regulating the size of the ow opening around the periphery of element 28.

The peripheral edge portions of the diaphragm are clampedv against the lower surface of housing body by means of the element 12, the space immediately below the diaphragm thereby constituting a dead-ended passageway or control chamber 36, the function of which is to receive a stream of control gas from the pilot passageway 38 so as to establish a substantially constant pressure in the outlet chamber 24.

The control passageway 38 initially receives its supply of gas through a conventional filter disk 40 which is seated within a recess 42 formed in the lower surface of the upper housing body 14. As the gas is discharged from the filter disk it travels upwardly through a port 44 and into a small chamber 46 (FIG. 2) in which is disposed a valve element 48. The valve element is arranged to open and close against a seat S0, a spring 52 being provided to force the valve to its seated position, and an electromagnet assembly S4 being provided to hold the valve element in its illustrated open position.

The assembly shown in FIG. 2 constitutes a conventional safety pilot shut-ofl, its purpose being to automatically cut off the ow to the burner pilot in the event that the pilot flame should for any reason be extinguished.

This safety shut-off utilizes a thermo-couple (not shown) which is adapted to be located in heat transfer relation to the pilot llame and to have an electrical lead connected with the electro-magnet assembly 54, the arrangement being such that in the presence of a pilot flame the thermo-couple automatically generates an electric current suiiicient to energize the electro-magnet 54 to hold the valve element 48 in the open position. The current generated by the thermo-couple, however, is normally not of sullicient magnitude to enable the electromagnet 54 to move the valve element from the closed position to the open position.

In order to move the valve element 48 to its open position there is provided a manually-operated device indicated generally by numeral 56. This device comprises a manually operable plunger 58 which is normally held in its illustrated position by means of a compression spring 60. The plunger is provided with a stem 62 which has a tip portion 64 located to strike the central portion of the valve element 48 when the plunger is manually pushed inwardly. Thus, during manual operation of the plunger the valve element 48 is automatically moved to its open position so as to permit a ow of gas from the' chamber 46 into the chamber 66. The chamber 66 may feed the fuel gas into a pilot line which is suitably connected into the valve, as for example into the threaded opening 68.

The serviceman or householder will normally hold the plunger in the depressed position for a short period of time, as for example twenty seconds, and the pilot flame will thereby operate on the thermo-couple to generate an electric current therein, the arrangement being such that the electro-magnet 54 thereafter holds the valve element 48 in its open position.

The present invention is not directly concerned with the operation or construction of the above-described safety pilot reset means, and said means is only described and illustrated herein because of its use in the illustrated valve and because of its pertinence to the general operation thereof.

In the illustrated embodiment the above-described chamber 46 connects with a passageway 70 which feeds fuel under pressure into a chamber 72, said chamber having a solenoid 74 suitably mounted therein. The solenoid may be of conventional construction and may be provided with suitable leads and external terminals, one lead and one terminal being shown in FIG. l at 76 and 78, respectively. In the usual installation the terminals for the solenoid are connected with external leads from the conventional room thermostat, and the solenoid is arranged to operate the conventional valve element 80 for controlling the flow of gas under pressure into the small pilot passageway 82. The operation is such that when the room thermostat calls for heat from the furnace, solenoid 74 is automatically energized to open the valve element 80. The gas thereby flows from chamber 72 into the passageway 82 and thence through a small opening 84 formed in the upper Wall of valve body 10. This small flow is only a fraction of the capacity of the main valve (i.e. the flow possible when port 22 is fully opened), but as previously indicated this by-pass or start-up flow is suflicient to feed the main burner with enough fuel to operate same without the pile-up of explosive gases in the combustion chamber of the furnace. The by-pass opening 84 is therefore of material advantage in operation of the gas valve at the start-up period.

After the start-up period it is desired that the gas Valve deliver its full capacity at its rated output pressure irrespective of substantial uctuations in the inlet pressure. The pressure regulation in the illustrated valve is obtained automatically by operation of the pilot regulator or stabilizer designated generally by numeral 86 in FIG. 1. This regulator comprises a small diaphragm 88 which is biased downwardly by means of a light compression spring 90. The diaphragm operatively connects With a flow-throttling element 92 by means of a stem 94, the arrangement being such that movement of the diaphragm is elfective to control the quantity of liuid passing through port 96. In this connection it will be seen that the regulator is moved back and forth by the opposing forces from the pressure in the chamber 98 and spring 90. Thus any tendency of the pressure in chamber 98 to rise above the design value will cause the diaphragm to be moved up so as to advance the valve element 92 toward a position fully throttling the ow through port 96. As a result the pressure in chamber 98 will be throttled or reduced so as to permit the spring to move the diaphragm 88 downwardly in a manner tending to provide a substantially constant pressure in chamber 98. The result is a closely stabilized or regulated pressure in chamber 98 irrespective of substantial variations in the pressure of the fluid supplied to the passage 82. The stabilized pressure from chamber 98 is fed to the previously described line 38 via a restrictor 100 best shown in FIG. 3.

As shown in FIG. 3 the restrictor 100 comprises a generally cylindrical body member having a press fit within a counter bore in the valve body 10, said cylindrical member and counter bore being so dirnensioned as to enable portion 102 of the member to project above the face of the valve body 10. The projecting portion of restrictor 100 is provided with a small orilice 104 therethrough. The size of this orilice determines the rate of opening of the main valve, and it is desirable therefore that this orifice be of precision formation. The orifice may be of different sizes depending on the desired speed of opening of the valve, but in an illustrative valve construction the orifice may have an area less than 0.00005 square inch, giving the valve a lag of about ve seconds between opening of element 80 and opening of main element 28. In general the larger the size of the orice the less the lag between opening of element 80 and opening of element 28. By making the restrictor as an insert member as shown in the drawings the time lag characteristic can be varied by insert replacement procedures without need for extensive parts duplication, valve body redesign, or parts inventory.

In operation of the illustrated valve, assuming that the pilot llame is on and the reset structure of FIG. 2 open, with solenoid 74 in a position closing the passage 82 there is no flow of gas into chamber 36 or chamber 24, and valve element 28 is held closed by weight of the parts and the inlet chamber pressure. When the room thermostat calls for heat the solenoid 74 is energized to open the passageway 82, which action causes a small stream of gas to flow through the passageway 84 and thence to the main burner. Additionally there is a flow of gas into chamber 98 and thence through line 38 to the underside of diaphragm 30. The restrictor 100 appreciably retards this iiow so that some time elapses before an operating pressure is developed in chamber 36. This elapsed period may be varied by the construction of the restrictor 100 as previously stated. In the usual installation a restrictor having a diameter of about .005 inch to .008 inch will be employed to give a time lag of about live seconds between energization of the solenoid 74 and an upward movement of the diaphragm 30. Du'ring this five second interval the total tlow out of the valve takes place via the passageway 84, the arrangement being such as to provide the desired ignition of the main burner and an orderly clearing away of the static air column in the stack. During normal burner operation the application of a control pressure in line 38 will establish a regulated pressure in outlet chamber 24.

In operation any tendency of the chamber 24 pressure to increase will of course depress the diaphragm 30 so as to throttle flow through port 22 in a manner to choke the pressure admitted to chamber 24. Choking of the chamber 24 pressure decreases the resistance to upward detiection of the diaphragm by the pressure in chamber 36, and the diaphragm is therefore moved very slightly upward so as to increase the opening through port 22 and thereby re-establish the desired pressure in chamber 24. The action of the illustrated valve is such that diaphragm 30 is effective to sense variations in chamber 24 pressure so as to regulate the chamber 24 pressure at a substantially constant value irrespective of substantial variations in pressure of the fluid supplied to chamber 1S.

In some installations it is desirable to be able to close valve 28 very quickly when the room thermostat is satisfied. This is the case particularly in burners having a tendency to pop back when the fuel supply pressure falls below a design value. In these burners if the flow of fuel to the burner is slowly throttled there is a tendency for the air adjacent the burner orifices to ow in a reverse direction from the ambient into the burner head and back toward the fuel supply. This backward ow of air causes the combustion to take place within the head rather than externally at the orifices, and there is an audible popping action, together with a sucking of the air from adjacent the pilot flame which sometimes results in extinguishment of the pilot llame.

The illustrated valve has special provision for eliminating this slow closing feature which is undesirable in certain installations as above stated. This anti-slow closing structure takes the form of a check valve 108 positioned within a vent line at 110 and 111. It will be seen from FiG. l that this vent line extends between passage 38 and outlet chamber 24. During normal opeartion of the apparatus the chamber 98 pressure forces check valve 10S to seat against the spherical seat 112, and there is no flow in the vent line. However, when the room thermostat and solenoid 74 cooperate to close valve element 80 the pressure in chamber 98 is automatically decreased so that the pressure in chamber 36 is allowed to act backwardly through line 38 and against the underside of ball 108 so as to raise said ball and vent the gas into the outlet chamber 24. By thus venting the chamber 36 pressure the outlet chamber pressure is effective to depress the diaphragm 30 for thereby closing the valve element 28. As above noted, the function of ball check 108 is to provide a quick closing of valve element 28 when the room thermostat is satisfied.. Without vent 110 and check 168 chamber 36 would be vented only very slowly (i.e. through the orifice at 102) and valve element 28 would close at a relatively slow rate. Without check 10.8 the restrictor i) would not be effective as a retarding device during the furnace start-up period.

From the above brief description it will be seen that the illustrated valve is of particular advantage in the provision of the passage constructions at 84, 102 and 110. The passage structures at 84 and 102 are of advantage in that they cooperate to enable the valve to deliver a relatively small charge of fuel to the burner at the start-up period, the action being such as to enable the pilot flame and burner orifices to better burn the fuel supplied through the main burner and to discharge the burned fuel without the occurrence of explosions within the combustion chamber or furnace room.

The restrictor at 102 is of particular advantage in that it automatically retards the diaphragm 30 from fully opening the valve element 28 until the passageway 84 has delivered its desired small volume of fuel to the burner for a short period of time. The presence of passageway 84 does not interfere with pressure regulation during the main portion of operation of the burner since the small amount of fuel continuously flowing through passage 84 discharges into the outlet chamber 24 and is insuflicient by itself to introduce an error in the pressure regulating function. In this connection any tendency of the fluid from passage 84 to decrease the pressure in chamber 24 is automatically sensed by the diaphragm 3@ so that the diaphragm takes this pressure variation into account as it controls the position of valve element 28.

The vent construction at is of particular advantage during shutdown of the burner since it serves as a means for quickly venting the pressure from chamber 36 so as to promote quick closing of valve element 28. Such a quick closing action is desirable in certain installations wherein the burner would otherwise tend to have a popback action on slow throttling of the fuel supply. It will be noted that the vent passage 110 communicates with chamber 98 so that during the application of pressure to the underside of diaphragm 30 check 10S automatically seals .against seat 112 in a manner to allow restrictor 102 to perform its time lag control function on the diaphragm 30.

The drawings show particular constructions for the component parts and particular arrangements of the component parts. However, it will be appreciated that some changes can be made in the design of the individual parts and in their manner of use with one another without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. In a tiuid pressure regulating valve,

a valve body defining a uid inlet chamber and a fluid outlet chamber with a main valve port therebetween, y a main valve element controlling flow through said main valve port,

movable wall means responsive to variations in outlet chamber pressure for controlling operation of said main valve element, means defining a pilot passageway for diverting partial load working fluid from said inlet chamber around said main valve port and into said outlet chamber, the size of said passageway being suiiicient to establish a start-up iow, electrically operated valve means for opening and closing said pilot passageway, means defining a control passageway for directing part of the iiuid from said electrically operated valve means against said movable wall means to operate said main valve element,

pressure stabilizing means operable on fluid in said control passage to stabilize iiuid pressure therein prior to application against said movable wall means,

and a restriction in said control passage for retarding initial application of stabilized pressure against said movable wall means to provide a time lag before opening of the main valve during which the only flow is that issuing through said pilot passageway.

2. The combination of claim 1 wherein the restriction is sized so that the time lag is about five seconds.

3. The combination of claim l wherein the restriction provides an orifice having an area less than .00005 square inch. K

4. The combination of claim 1 and further comprising a vent extending from the last-named passageway to said outlet chamber for quickly exhausting gas from the movl' able wall means.

5. The combination of claim 4 and further comprising a check valve in said vent for preventing liow therethrough in the direction of the movable wall means.

6. The combination of claim 5 and further comprising means placing the portion of the vent downstream of the check valve in communiaction with a portion of the lastnamed passageway upstream of the restriction.

7. The combination of claim l wherein said restriction in said control passageway is positioned between the stabilizing means and movable wall means; and further in. cluding a vent line extending from a portion of the passageway between the restriction and movable wall means into gas pressure communication with the outlet chamber; a check Valve in said vent line preventing flow into the pasageway from the outlet chamber; and means placing the downstream area of the check valve in communication with a portion of the passageway located between the stabilizing means and restriction.

8. The combination comprising a main valve; an operator responsive to variation in main valve output pressure to regulate said pressure; means defining a pilot passageway for applying a control pressure on said operator in opposition to the main output pressure; regulator means in said pilot passageway for stabilizing the control pressure applied to the operator; a restriction in the pilot passageway between the regulator means and operator; a Vent connected between the restriction output and the main output pressure to exhaust excess control pressure from the operator; a check valve in said vent preventing reverse liow therein; and means applying the control pressure onto the back side of the check valve to prevent the control pressure from unseating the check valve during application thereof onto the operator.

9. In a flow control and pressure regulator valve, a Valve body defining a iluid inlet chamber and a fluid outlet chamber with a valve port therebetween, a main valve controlling flow through said port, an operator connected to said main valve and having one side exposed to the fluid in said outlet chamber and an opposite side exposed to a control chamber isolated from said outlet chamber, a partial load fluid conduit connecting said inlet chamber to said outlet chamber independently of said main valve and port, the size of said partial load conduit being suicient to establish a start-up flow, a partial load valve controlling iow through said partial load conduit, a iiuid flow control passage connecting said partial load conduit and said control chamber, and a restriction in said control passage.

l0. A valve comprising a housing having an inlet opening and an outlet opening with a main passage communicating therebetween,

a Valve member in said main passage and movable between closed and open positions for controlling the iiow of gas therethrough,

a diaphragm for moving said valve member and having one face exposed to valve outlet pressure,

means for controlling the position of said valve member including means forming a pressure chamber adjacent the other face of said diaphragm,

means forming an auxiliary gas passage from said valve inlet opening to said pressure chamber permitting a iiow of gas from said inlet opening to said pressure chamber,

electromagnetically operated valve means in said auX- iliary passage operable to block said auxiliary passage when deenergized and to unblock said passage when energized,

an orifice downstream of said electromagnetically operated Valve means providing restricted gas flow from said auxiliary passage to the outlet opening of said valve,

a pressure responsive valve means in said auxiliary passage downstream of said orifice for maintaining 8 the`V pressure in said pressure chamber substantially constant despite variations in pressure at said inlet opening,

a restricted outlet passage downstream of said pressure responsive valve means joining said auxiliary passage and said valve outlet opening and permitting restricted gas ilow therebetween,

and a one-way liow restricting means in said auxiliary passage between said restricted outlet passage and the terminus of said auxiliary passage at said pressure chamber,

whereby upon energization of said electromagnetically operated valve means gas flows through said oriiice into said valve outlet opening initially establishing a relatively low gas pressure therein,

the gas pressure in said valve outlet opening thereafter increasing at a rate which is a direct function of the rate of gas ow through said one-way flow restricting means,

and subsequently the pressure in said valve outlet opening reaching a maximum value as the gas pressure in said pressure chamber balances the pressure in said valve outlet opening.

1l. In a fluid flow control and pressure regulating valve,

a Valve body defining a fluid inlet chamber and a liuid outlet chamber with a main valve port therebetween,

a main valve controlling flow through said main valve port,

a movable operator responsive to variations in outlet chamber pressure for controlling operation of said main valve,

means defining a pilot passageway for diverting partial load working iiuid from said inlet chamber around said main valve and port to said outlet chamber, the size of said passageway being suliicient to establish a start-up iiow,

means defining a control passage for directing part of the fluid from said pilot passageway against said operator to operate said main Valve,

and a restriction in said control passageway for retarding initial application of pressure against said operator to provide a time lag before opening of the main valve during which the only flow is start-up iiow issuing through said pilot passageway.

l2. In a fluid flow control and pressure regulating valve,

a valve body defining a uid inlet chamber and a uid outlet chamber with a main valve port therebetween,

a main valve controlling iiow through said main valve port,

a movable operator responsive to variations in outlet chamber pressure for controlling operation of said main valve,

means defining a pilot passageway for diverting partial load working uid from said inlet chamber around said main valve and port and into said outlet chamber, the size of said passageway being suliicient to establish start-up llow,

valve means for opening and closing said pilot passageway,

means defining a control passageway for directing part of the fluid from said pilot passageway valve against said movable operator to operate said main valve,

pressure stabilizing means operable on flow in said control passageway to stabilize fluid pressure therein prior to application against said movable operator,

a restriction in said control passage for retarding initial application of stabilized pressure against said operator to provide a time lag before opening of said main valve during which the only flow to said outlet chamber is start-up ow issuing through said pilot passageway,

a vent leading from a point in said control passageway between said restriction and said operator to said uid outlet chamber,

and a check V alve in said vent permitting flow only from said control passageway to said fluid outlet chamber.

References Cited in the le of this patent UNITED STATES PATENTS Horridge 10 Jacobsson Jan. 20, 1942 Gille Nov. 9, 1943 Griswold Dec. 27, 1949 Nuenemann July 25, 1950 Tavener Sept. 1, 1959 Cooper Apr. 18, 1961 

1. IN A FLUID PRESSURE REGULATING VALVE, A VALVE BODY DEFINING A FLUID INLET CHAMBER AND A FLUID OUTLET CHAMBER WITH A MAIN VALVE PORT THEREBETWEEN, A MAIN VALVE ELEMENT CONTROLLING FLOW THROUGH SAID MAIN VALVE PORT, MOVABLE WALL MEANS RESPONSIVE TO VARIATIONS IN OUTLET CHAMBER PRESSURE FOR CONTROLLING OPERATION OF SAID MAIN VALVE ELEMENT, MEANS DEFINING A PILOT PASSAGEWAY FOR DIVERTING PARTIAL LOAD WORKING FLUID FROM SAID INLET CHAMBER AROUND SAID MAIN VALVE PORT AND INTO SAID OUTLET CHAMBER, THE SIZE OF SAID PASSAGEWAY BEING SUFFICIENT TO ESTABLISH A START-UP FLOW, ELECTRICALLY OPERATED VALVE MEANS FOR OPENING AND CLOSING SAID PILOT PASSAGEWAY, MEANS DEFINING A CONTROL PASSAGEWAY FOR DIRECTING PART OF THE FLUID FROM SAID ELECTRICALLY OPERATED VALVE MEANS AGAINST SAID MOVABLE WALL MEANS TO OPERATE SAID MAIN VALVE ELEMENT, PRESSURE STABLIZING MEANS OPERABLE ON FLUID IN SAID CONTROL PASSAGE TO STABILIZE FLUID PRESSURE THEREIN PRIOR TO APPLICATION AGAINST SAID MOVABLE WALL MEANS, AND A RESTRICTION IN SAID CONTROL PASSAGE FOR RETARDING INITIAL APPLICATION OF STABILIZED PRESSURE AGAINST SAID MOVABLE WALL MEANS TO PROVIDE A TIME LAG BEFORE OPENING OF THE MAIN VALVE DURING WHICH THE ONLY FLOW IS THAT ISSUING THROUGH SAID PILOT PASSAGEWAY. 